Blower



Dec. 31, 1940. w. o. BEHRENS 2,227,373

BLOWER Filed Feb. 25, 1938 Patented Dec. 31, 1940 UNITED STATES -TENTQFFICE Claims.

The invention relates to blowers and more particularly to the type ofblower adapted to deliver separate supplies of air at different volumesor pressures.

The present invention embodies improvements particularly well adaptedfor use in connection with the burners disclosed in my copendingapplications, Serial No. 90,232 filed July 11, 1936 and Serial No.150,279 filed June 25, 1937.

An object of the invention is to provide a new and improved fan blowerconstruction requiring a minimum of horse power expenditure in operationdue to its simplicity of construction and the ease of air flowtherethrough. More specifically stated, it is an object of the inventionto provide a novel rotary fan blower of this type having a single airintake opening, a low pressure outlet and a high pressure outlet, saidblower embodying new and improved features of construction rendering itparticularly well adapted for efficient operation in supplying low andhigh pressure air for an oil burner utilizing both primary and secondaryforced draft.

Other objects and advantages will become apparent in the followingdescription and from the accompanying drawing in which:

Figure 1 is a longitudinal sectional view of an oil burner embodying thefeatures of the invention.

Fig. 2 is an end view in elevation of a rotary blower with a section ofthe blower broken away to show the underlying construction.

While the invention issusceptible of various modifications andalternative constructions, I have shown in the drawing and will hereindescribe in detail, the preferred embodiment, but

it is to be understood that I do not thereby intend to limit theinvention to the specific form disclosed, but intend to cover allmodifications and alternative constructions falling within the spiritand scope of the invention as expressed in the appended claims.

The oil burner shown inthe drawing for purposes of disclosure is of thetypeadapted to dis- 4:5 charge a turbulent mixture of atomized fuel andoil conditioned for. efficient combustion, preferably into a sealedfurnace. The blower of the present invention is embodied in a burnerhaving a primary air nozzle ill for supplying high pressure low volumeair to the furnace, said nozzle being coaxially alined with acircumscrib-ing secondary air nozzle ii of generally Venturi shaperigidly secured in and adapted to discharge relatively low pressure highvolume air into an end 5 opening l2 in a refractory furnace wall It. A

burner front plate I4 is secured against the exterior of the wall l3 andhas an opening IE to receive the nozzles. An annular flange portion [6of the nozzle I l is secured to the plate M to hold the nozzles inplace.

Low pressurehigh volume air is supplied to the secondary air nozzle andrelatively high pressure low volume air is supplied to the primarynozzle by means of a rotary blower (indicated generally at ll) enclosedwithin a housing Hi. The housing 18, together with a cover [9, issuitably supported to form the outer wall of an air passage 29 openingto the nozzle II and to the source of secondary air supply. The cover I9is formed with a suitably apertured plate member 2| extendingtransversely oi" the axis of the burner and terminating in an inner ring22 to provide the stationary element of a damper for throttling thesecondary air supply from the blower. A rotary damper member 23,similarly apertured, is operatively disposed against the plate member 2!and is adjustable by means of a rod 25 pivotally connected to one sidethereof and extending out of the housing.

The primary air nozzle is mounted on the end of a tube 26 whichconstitutes the outlet from the source of primary high pressure air. Thetube 26 is supported in the ring 22 in spaced relation to the coverplate I!) to provide an inner wall for the secondary air passage 20.

An important feature of the instant invention resides in the provisionof a novel blower construction for providing both primary and secondaryair to the'nozzles by means of a single unitary rotary fan blower. tothe free passage of air therethrough is one of the objectionablecharacteristics of fan blowers heretofore employed. It is desirable inblowers of this type to provide an air flow path with a minimum ofbaffle walls and partitions causing scrubbing of the air and an increasein the frictional resistance of the fan to the passage of airtherethrough.

To this end, the blower embodied in the present invention is constructedof simple and etficient design to reduce frictional loss. Theproportional amounts of primary and secondary air delivered by the fanare controlled solely by the relative width of its peripheral dischargeopenings, the fan embodying only one axial air intake opening. Thefrictional loss necessarily inherent in the ordinary compound disk fanhaving more than one intake opening is thus obviated. The single axialintake opens to a single set of impeller blades defining generallyradially extend- Frictional resistance ing air passages through whichthe air is impelled by the centrifugal force created by rotation of thefan. The radially impelled air is then divided into separate radialstreams, part being discharged immediately as secondary low pressure airthrough a peripheral outlet and the remainder being subjected to anadditional impulse to provide primary high pressure air which isdischarged peripherally of the fan at a greater radial distance from theaxis. Lateral separation of the air stream is not effected until the airreaches the secondary discharge, thus avoiding the necessity forseparate partitions and consequent frictional resistance inherent insuch partitioned constructions. This simplified fan constructionembodies the additional advantages of light weight and compactness, thusreducing the bearing friction and overhang to increase the efficiency ofthe fan.

The fan or impeller ll, illustrating one embodiment of the invention forpurposes of disclosure of the above mentioned principles, comprises aradially extending disk 34 fixed for rotation with a drive shaft 21extending axially of the burner. Integral with one side of the disk area plurality of spaced impeller blades 32 slightly inclined to theradius. These blades extend longitudinally of the shaft 21 and at theirinner end edges may be slightly spaced therefrom. An annular ring ordisk 33 of lesser diameter than the disk 34 is integral with the freeside edges of the blades in spaced relation to the disk 34 and definesan axial air inlet opening 28 com municating with the motor housing 43.It will be seen that the disks 34 and 33 and the blades 32 definegenerally radial passages 29 in communication at their inner ends withthe air inlet 28 and discharging peripherally of the fan.

The outer ends of the blades 32 are stepped radially inwardly from theexternal periphery of the disk 34 to the periphery of the disk 33.Alternating with the narrowed portions of the blades 32, are a pluralityof short generally radial blades 32 also integral with the disk 34. Thefree side edges of the blades 32 and of the narrowed portions of theblades 32 are integral with an annular disk 33 spaced from the disk 34to define narrowed supplemental air passages 29 communicating at theirinner ends with the passages 2 9 and discharging peripherally of thedisks 33 and 34 (as indicated at 3!). It will be seen that the innerperiphery of the annular disk 33 divides the passages 29 at their outerends into separate portions longitudinally of the shaft 21. Thoseportions of the stepped blades 32 lying on the side of the disk 33toward the disk 33* terminate at the inner periphery of said disk 33 inperipheral discharge openings 33 while those portions of the blades onthe inner side of the disk 33 are elongated to define, together with theblades 32 and the disks 33 and 34, the supplemental passages 29*.

Rotation of the fan creates a suction at the inlet opening 28 drawingair through the motor housing 40 and into the passages 29 where it isdirected radially by the centrifugal force created by rotation of theimpeller. The radially directed stream is divided into separate streamsby the disk 33,'part being discharged immediately upon separationthrough the peripheral discharge opening 30 as secondary air. Theremainder is subjected to an additional impulse in the passages 29 toimpart a greater pressure thereto and is discharged through theperipheral discharge openings 3| as primary air. Since the air pressuredelivered by a rotary disk fan is a function of the tip speed of theblades, it will be apparent that the portion of the air stream deliveredthrough the discharge 3| as primary air will be under greater pressurethan that delivered through the openings 33 as secondary air, theexternal circles of revolution of the stepped blade formationdetermining the pressures. The discharge 30 may be located at a radialdistance from the axis substantially one half that of the discharge 3|.It is preferred that a greater volume of secondary air be provided thanprimary air, and to this end the secondary air discharge opening 39 ismade of greater width than the primary air discharge opening 3!.Accordingly, the proportionate volumes of primary and secondary airdelivered may be effectively controlled by providing appropriaterelative Widths to the discharge openings.

An internal housing 34 encloses the high pressure side of the fan and,together with a circular baffle or guide plate 35 serves to direct airfrom the primary air discharge opening to the interior of the tube 23.The housing 34 has an end wall 36 which closely encircles the shortportions of the blades 32 adjacent the disk 33, and which together withthe housing l3 forms an air passage 31 between the low pressuredischarge 3!! and the passage 20 to the secondary air nozzle. The lowpressure side of the blower, although smaller in diameter than the highpressure side, discharges substantially parallel thereto into thepassage 31 between said housings and hence into the passage 29 to thesecondary air nozzle. The nozzles l0 and II may be suitably providedwith sets of spaced helical vanes 38 and 39, respectively, said vaneshaving opposite inclinations to insure an intimate fuel mixture and fineatomization.

It will be apparent from the foregoing that a novel blower contructionhas been provided which may be operated with greater efiiciency than hasbeen possible heretofore. Both primary and secondary air may beeffectively introduced into the burner by means of a simple and compactblower unit of the type herein disclosed. The air is introduced into theblower through a single axial inlet opening and is impelled radially toa peripheral discharge opening where the air stream is divided, partbeing discharged through said opening and the remainder, continuing itsradial flow, is impelled to a second peripheral discharge opening ofgreater diameter where it is discharged under greater pressure. Such aconstruction greatly reduces the frictional resistance to the passage ofair through the blower thus increasing the efliciency of the blower andat the same time the weight of the fan is materially reduced resultingin a substantial saving in the cost of manufacture.

As fully described in my copending applications, a cylindrical housing40 encloses the inlet side of the housing l3, said cylindrical housinghaving a plurality of air inlet openings 4| opening from the atmosphere.The inner end Wall of the housing 40 is formed with an axial outletopening 42 communicating with the blower intake 28 and in directregistration and close interfitting relation therewith. The shaft 21extends into the housing 40 where it may be suitably journaled in spacedbearings 44 and driven by any desired driving means as an electric motor45. A suitable fuel pump (not shown) may be provided and driven from aworm gear mechanism (indicated at 46) An atomizing cup 41 and fuelnozzle (it are mounted on the inner end of the shaft El for rotationtherewith and communicate with an elongated fuel supply tube fill withinthe shaft. A valve mechanism (indicated generally at 5b) is located atthe opposite end of the shaft and is interconnected with the rod 25 forjointly controlling the supply of fuel and secondary air.

I claim as my invention:

1. A rotary fan blower adapted to deliver air under different pressures,said blower comprising a longitudinally disposed drive shaft, a set oflongitudinally and generally radially extending spaced impeller bladesfixed for rotation. with said shaft, the outer ends of said blades beingstepped to provide opposite side portions of different widths andlengths, a radially disposed disk secured to the long side edges of saidblades and extending substantially throughout the length of said blades,an annular disk secured to the free short side edges of said blades anddefining an axial air inlet opening to the inner ends of said blades, anannular disk secured to the intermediate side edges of the steppedportions of said blades and terminating at a point spaced substantiallyoutwardly from the inner ends of said blades, whereby said blades andsaid disks define generally radial passages communieating at their innerends with the air inlet and discharging peripherally in separate stagesat difierent radial distances as defined by said stepped blade portions,and separate air delivery means opening respectively fro-m theperipheries of said stepped blade portions.

2. A fan blower for delivering air at different pressures, said fanblower having in combination a drive shaft, a plurality of bladesperipherally spaced about said shaft and extending outwardly thereof todefine generally radial air passages,

40 each blade having an outer end of stepped formation with one sideportion relatively short and having a relatively small circle ofrevolution, and with the other side portion relatively long and having arelatively large circle of revolution, a 45 closed disk rigidlyconnected with the long side edges of said blades and fixed on saidshaft for rotation therewith, an annular disk rigidly connected with theopposed short side edges of said blades and defining a common axial airinlet 50 passage opening to the inner ends of said radial passages, anintermediate annular disk closely encircling the first mentioned sideportion and rigidly connected with the intermediate side edges of saidblades in spaced relation to said 55 first mentioned disk to definesupplemental air passages, said intermediate annular disk having aradial extent limited substantially to the distance between said circlesof revolution, and independent air directing means communicating re- 60spectively with the outer end edges of the re1atively short sideportions of the blades and with the relatively long side portions of theblades for delivering separate supplies of air under differentpressures.

3. A blower adapted to deliver separate supplies of air at differentvolumes and pressures, said blower comprising a drive shaft, a radiallyextending disk fixed to said shaft for rotation therewith, a pluralityof spaced impeller blades 70 integral with said disk and slightlyinclined to the radius, a second disk of relatively smaller outsidediameter integral with the inner portions of the free side edges of saidblades, an axial air inlet in said second disk circumscribing the shaft,said disks and said blades defining generally radial airpas-sagescommunicating at their inner ends with said intake anddischarging peripherally, the outer free edge portions of said bladesbeing narrowed in width toward the first mentioned disk and radiallyinwardly to the periphery of the second disk, anv annular disk integralwith the free side edges of the narrowed portions of the blades andfixed in spaced relation to said first mentioned disk, said annular diskextending radially inwardly only to the extent of said narrowedportions, said annular disk together with the narrowed portions of theblades and the outer annular area of said first mentioned disk definingextended generally radial air passages communicating at their inner endswith a longitudinal portion of the first mentioned radial air passagesand discharging peripherally of the last mentioned disks, and separateair directing means communicating with said passages for delivering airtherefrom.

4. A rotary fan blower adapted to deliver air under different pressures,said blower comprising a longitudinally disposed drive shaft, a set oflongitudinally and generally radially extending spaced impeller bladesfixed for rotation with said shaft, each of said blades having an. outerend of stepped formation, radially disposed disks along the free sideedges of said blades, an axial air inlet in one disk opening to theinner ends of said blades, said blades and said disks defining generallyradial passages communicating at their inner ends with said air inletand discharging peripherally, and means including an intermediateannular disk extending radially only along the intermediate side edgesof the stepped formations on said blades and defining two separate airdelivery passages opening respectively from opposite peripheral sideportions of said radial passages to provide separate air supplies.

5. A rotary fan blower comprising, in combination, a drive shaft, a diskfixed for rotation with said shaft, a single set of generallylongitudinally and radially extending spaced impeller blades fixed tosaid disk for rotation with said shaft and substantially alignedperipherally about said shaft, the outer end of each blade being steppedlongitudinally to provide one side portion with a relatively smallexternal circle of revolution and the other side portion with a.relatively large external circle of revolution, a radially disposed diskrigidly connected along the short side edges of said blades, an axialair inlet in one of said disks opening to the inner ends of the spacesbetween said blades, and an annular disk disposed intermediately of thefirst mentioned disks and secured along the free side edges of theintermediate stepped portions of said blades, said last mentioned diskextending inwardly only to the periphery of said small circle ofrevolution, said blades and said disks defining generally radialpassages communicating at their inner ends with said air inlet, each ofsaid passages discharging from the stepped portions of said blades atdifferent peripheral circles of revolution.

WILLIAM O. BEHRENS.

